The Redfin Darter is found the southeast corner of Kansas, most commonly in the Spring, Neosho, Verdigris, Elk and Caney river basins. There are indications of a limited relict population in Cowley County, in the eastern part of the Arkansas River basin. The Redfin Darter inhabits clear streams with low to moderate gradient with small gravel, sometimes mixed with sand, broken shale or bedrock. In March, breeding males exhibit brightly colored fins and scattered red spots. Its range is restricted to Kansas, Missouri, Oklahoma and Arkansas, and is considered critically imperiled in Missouri. Historic records of collections are sparse, and of single or a low number of individuals.